The present invention relates generally to automatic determination of at least one attribute of a liquid substance. More particularly, the invention relates to a monitoring unit, a method, and a computer readable medium.
There are many areas where efficient and reliable handling of liquid substances is important, for instance in connection with production and processing of foodstuffs. Moreover, automatic milking solutions are becoming increasingly efficient and sophisticated. Today, there is also a strong demand for flexible and animal-friendly milk production. For example, so-called milking robots have been introduced, which enable animals to autonomously decide when they are to be milked. Milking robots are advantageous because they reduce the amount of manual labor involved in milking. Milking robots are also desirable from an animal health point-of-view, since thereby it is uncomplicated to extract milk more frequently than by applying the existing alternative solutions, and in general, high-frequency milking vouches for a good udder health. However, milking robots may be somewhat problematic because these machines are often operated without any human operator being present. This, in turn, renders a safe and reliable operation highly important. One aspect of such an operation is that problems related to unsatisfying milk quality must be resolved automatically. For example it is necessary to automatically detect unacceptably high concentrations certain constituents in the milk, such that adequate measures can be taken promptly.
U.S. Pat. No. 4,678,995 describes an apparatus and method for determining the presence of specific substances in a sample, e.g. of tissue, by nuclear magnetic resonance (NMR) and then obtaining a high-resolution NMR image of these substances.
U.S. Pat. No. 7,141,978 discloses a solution for analyzing fluid samples by means of an NMR probe comprising multiple NMR detection sites.
WO 00/39578 reveals a method and apparatus for estimation of a cell count in a body fluid. Here, a mid-IR spectrum is recorded and the spectral information therein serves as a basis for deriving a number of cells in the body fluid. This document also briefly mentions the possibility to employ NMR spectroscopy.
US 2009/0278685 describes methods and systems for calibration of radio-frequency identification (RFID) sensors involving impedance measuring by determining a complex impedance spectrum, a phase angle and/or a magnitude of the impedance. Inter alia, the document mentions that the RFID sensors may be adapted to measure physical, chemical and biological parameters; each sensor can have a digital ID and be calibrated to accurately react to a parameter of interest through changes in measurements of the sensor's complex impedance.
U.S. Pat. No. 7,219,024 discloses a system, method and program product for determining in-place engineering properties, such as density and moisture content of certain engineering materials. A database, material model and sensor model are also shown. The document generally relates to material analysis, and to the field of impedance spectroscopy, and the determination of engineering properties of a material from the response to electromagnetic probing in a defined frequency spectrum.
U.S. Pat. No. 6,511,851 reveals a method for identifying a change in the composition of a liquid. Here, a time varying electrical or electromagnetical input signal is applied to the liquid in a range of frequencies encompassing a resonant frequency of an electrical circuit comprising the liquid. An impedance quantity is measured of said electrical circuit by means of the output signal as a function of the frequency of the time varying input signal in said range of frequencies. A resonant frequency of said electrical circuit is determined. After a change in the composition of the liquid, variation in the impedance quantity is measured at or near the previously determined resonant frequency of said electrical circuit. The variation in the impedance quantity is then related to the change in the composition.
WO 2008/076453 describes a flex fuel sensor, which is deployed in conjunction with a fuel transfer line, or at the bottom/side of a fuel tank. A radio-frequency signal at a constant frequency may be generated across a resonant circuit, which comprises an inductor and a printed circuit board trace capacitor, capacitor plates, semi cylindrical capacitor plates, or the like. Electromagnetic radiation is propagated into the passing fuel in the transfer pipe. The conductivity and dielectric properties of the fuel change the capacitance of the trace capacitor plates. These changes are proportional to the ethanol/alcohol content of the fuel, and are preferably detected by a microcontroller, or the like, and then transmitted to a flex fuel vehicle engine management system.